Ellie Goulding’s stay-happy secrets

At one of Ellie Goulding's recent New York City shows, the musician wore only a black-and-mesh number reminiscent of Cher's bodysuit from her "If I Could Turn Back Time" video—though with a bit more left to the imagination.

Of course, Goulding really has nothing to hide when it comes to her body, which she's worked hard to get. She's currently training for her fifth half marathon (she'd like to beat her personal best: a very respectable 1:41), yet explains that as a child "I was never that fit. I was sort of averagely good at sports, never bad but never really a standout, either."

By the time she turned 18, her body, she thought, was "genetically how it was meant to be. In my family, we've got big waists—a belly but not much of a bum or boobs."

Then she fell for a guy named Matt, 12 years her senior and the brother of a classmate, who helped change her life and body forever.

"I was completely taken in by him," she recalls. "He saw something in me—a talent, a drive—that I didn't even see in myself, and I loved having him around."

Matt taught her about healthy eating ("My mom was raising four kids on her own, so we ate whatever we wanted: cheap food, sugary cereal and such") and also turned her on to exercise.

"He'd say things like 'You need to look after yourself more.' So I started running, and suddenly I was addicted to fitness. I just knew that every day I needed to go out and run. I knew it was keeping me in a good place, even if I couldn't exactly explain how."

If her killer abs aren't a dead giveaway, seeing Goulding own the stage for 90 minutes straight without so much as a hint of breathlessness in her voice gives you a sense of how fit she's become.

"It's hard to stay motivated, but I feel like there's a very strong force pushing me to exercise. It's as if something—the universe, I don't know—is telling me, 'You need to always be as fit as you can be.' I've gained slightly different priorities while being on this planet, and one of them is to respect my body and to do as much as I can with it while I'm here."

Free running, another of her active hobbies, tests those limits.

"It's all about flexibility, agility and getting from one place to another in the most adventurous, inventive way possible," she explains, pointing to two empty chairs about 8 feet apart on the other side of the restaurant. "If you could convince yourself that jumping from that chair to the next was a life-or-death thing, you could most likely do it."

The sport has changed the way she sees everything.

"I'll go outside and jump between benches, pull myself up on things, crawl through things. I'll do anything that scares me. Once, I even walked across a log over a big ravine. I'd probably survive if I fell, but I would've been pretty hurt," she said, adding, "Free running makes you super f---ing fit. And the fitter you become, the more you can deal with s--- like that. It forces you to trust your body. It makes you realize that your body helps you more than you know."

A recent back injury—"I fell over in the bath, which is the least rock-and-roll way to get hurt"—sidelined her for a bit, but she's feeling stronger every day. "The reason I keep pushing myself is that I know I have strength that I haven't gotten yet."

For Goulding, fitness is never about aesthetics (though she admits she'd be up for posing for a lingerie campaign). "I don't have the perfect body, but I don't train to look good," she said. "That's just a cool bonus."